Kevin-Prince Boateng's father has revealed that his son has had a long-standing rivalry with Michael Ballack since the Germany captain talked down to him early in his Bundesliga career, though he denied Boateng tried to injure Ballack on purpose in Saturday's FA Cup final.Boateng's tackle on Ballack caused the Chelsea midfielder ankle ligament damage, and the injury was revealed on Monday to be severe enough to rule him out of what was likely to be his final World Cup in South Africa next month.There had been many post-match claims that Boateng, who has been selected to play for Ghana at the finals after failing to receive a call-up from his native Germany, went in to purposefully injure the captain of the side who pose the biggest threat to the Black Stars' progression from the World Cup group stage.But Boateng's father Prince denied such a conspiracy, though he did admit that his son has had a personal problem with Ballack since being goaded by him during a Bundesliga match in 2006."Kevin's the whipping boy once again," Prince Boateng told the Hamburg Morning Post. "It's always twice as bad when anything happens with a Boateng. It upsets me a lot."But you have to look at the whole story. [In 2006] Kevin had just scored his first goal for Hertha [Berlin]. Then they played against Bayern Munich. He had an argument with Ballack."Ballack said to him: 'You've scored one goal, and you think you are the best'. Kevin has never forgotten that. Unfortunately, Kevin isn't very diplomatic. But I am sure, even if he did foul Ballack, he didn't mean to injure him."The tackle - described as a "revenge attack" by the Bild newspaper - has unsurprisingly stirred up a storm in Germany, while Boateng had already come under presssure for opting to play for Ghana - his father's African homeland - instead of the country of his birth.In a further twist, Kevin-Prince could, if selected, face his brother and Germany squad-member Jerome when the nations clash in Johannesburg on June 23.Source: soccernet.espn.go.com